River Flood Warning 28, NWS Detroit, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
625 AM EST MON DEC 29 2008

.AVIATION...
MAIN CONCERN WILL BE WIND.  A CLIPPER SYSTEM WILL MOVE EAST ACROSS
NORTHERN MICHIGAN THIS AFTERNOON AND EVENING WHILE DEEPENING.  LOW
LEVEL GRADIENT WILL INCREASE DURING THE DAY INCREASING SURFACE WINDS
FROM THE SOUTHWEST. DIURNAL MIXING WILL BRING DOWN WIND GUSTS TO
AROUND 30 KTS MBS/FNT AND 25KTS DET/DTW THIS AFTERNOON AHEAD OF THE
FRONT.  STRONG DOWNWARD MOMENTUM BEHIND THE FRONT WILL BRING DOWN
WIND GUSTS UP TO 40 KTS FROM 21Z THROUGH 04Z WHILE WINDS WILL
BE SUSTAINED FROM THE WEST AROUND 20KTS...THEN WINDS WILL GRADUALLY
RELAX AS THE SYSTEM PULLS AWAY.  MOISTURE IS LIMITED WITH THIS SYSTEM SO
EXPECT VFR CONDITIONS EXCEPT FOR A BRIEF PERIOD OF BROKEN MVFR AT
MBS/FNT WITH FRONTAL PASSAGE.

&&

.SHORT TERM...TODAY

CLIPPER SYSTEM OVER MINNESOTA WILL TRACK QUICKLY EAST ACROSS THE
U.P. THIS AFTERNOON WITH SURFACE COLD FRONT SWEEPING THROUGH
SOUTHEAST MICHIGAN LATE AFTERNOON/EVENING.  THIS SYSTEM IS MOISTURE
STARVED WITH MAIN AREA OF PRECIP STAYING AROUND AND NORTH OF SURFACE
LOW.  WILL CONTINUE THE SLIGHT CHANCE FOR LIGHT SNOW ACROSS THE
NORTHERN SAGINAW VALLEY AND THUMB WITH THE FRONTAL PASSAGE WHERE
MOISTURE AND LIFT WILL BE SLIGHTLY DEEPER AND STRONGER.

THE MAIN CONCERN WITH THIS SYSTEM WILL BE WIND AS LOW LEVEL GRADIENT
TIGHTENS AS SURFACE LOW DEEPENS.  SOUTHWEST WINDS WILL INCREASE THIS
AFTERNOON TO AROUND 20 MPH SUSTAINED WITH GUSTS TO 30 MPH AS MIXING
HEIGHTS TAP INTO 30KT WINDS AT 925MB. LOW LEVEL WINDS BEHIND COLD
FRONT PASSAGE INCREASE EVEN MORE TO AT LEAST 40 KTS.  WITH STRONG
SUBSIDENCE BEHIND THE COLD FRONT...GUSTS SHOULD REACH 40 MPH LATE
TODAY INTO EARLY THIS EVENING.

INCREASING SOUTHWEST FLOW WILL ALSO BRING IN A DECENT QUICK SHOT OF
WARM AIR WITH TEMPERATURES REACHING THE 40S IN MOST AREAS.  THE
MORNING WILL START OFF MOSTLY CLEAR MOST OF THE AREA WITH CLOUDS
QUICKLY INCREASING BY AFTERNOON ACROSS THE NORTHERN TWO THIRDS OF
THE FORECAST AREA.  SOUTHERN AREAS SHOULD REMAIN PARTLY TO MOSTLY
SUNNY.

&&

.LONG TERM...

STRONG UPPER WAVE/SHORTWAVE TROUGH SEEN ON THE WATER VAPOR
IMAGERY QUICKLY APPROACHING THE PACIFIC NORTHWEST. THIS SYSTEM IS
ON TRACK TO MOVE THROUGH OUR AREA TUESDAY AFTERNOON-TUESDAY
NIGHT...WITH MODEL TRENDS OF THE GFS AND NAM ALL SHOWING A FASTER
AND FARTHER SOUTH SOLUTION...WITH THE SURFACE TRACK ALONG OR SOUTH
OF THE MICHIGAN BORDER...RESULTING IN A FAVORABLE TRACK FOR
ACCUMULATING SNOW OVER MUCH/ALL OF SOUTHEAST MICHIGAN. GOOD
ISENTROPIC ASCENT/MID LEVEL FGEN...AND AT LEAST 2 G/KG OF SPECIFIC
HUMIDITIES TO WORK WITH SHOULD RESULT IN MOST AREAS RECEIVING 2 TO
3 INCHES...WITH A SWATH OF 3 TO 4 INCHES (POSSIBLY UP TO 5 INCHES)
SOMEWHERE IN THE CWA (BEST BET ALONG THE I-69 CORRIDOR)...AS SNOW
TO LIQUID RATIOS LOOK FAVORABLE WITH AVERAGE 850-700 MB
TEMPERATURES AROUND -10 C TUESDAY AFTERNOON...FALLING INTO THE
NEGATIVE LOW TO MID TEENS DURING THE EVENING HOURS. STILL THINKING
LOCATIONS RIGHT ALONG THE OHIO BORDER WILL STRUGGLE TO SEE MUCH
SNOW (AN INCH OR LESS).

WITH THE LOW PRESSURE CONTINUING TO DEEPEN AT A RATHER STEADY RATE
(4 MB IN 6 HRS) AS IT PULLS AWAY...SNOW WILL BE BLOWING AROUND BY
WEDNESDAY MORNING WITH NORTHWEST WIND GUSTS AROUND 35 MPH
EXPECTED...SETTING UP A VERY COLD DAY ON WEDNESDAY...AS 850 MB TEMPS
HOLD IN THE NEGATIVE MID TEENS TO POSSIBLY UPPER NEGATIVE
TEENS...RESULTING IN MAXES ONLY IN THE LOW TO MID TWENTIES.

FRESH SNOW COVER AND A SURFACE RIDGE BUILDING OVER SOUTHERN LOWER
MICHIGAN WEDNESDAY NIGHT COULD SPELL MINS DOWN INTO THE SINGLE
NUMBERS TO AROUND ZERO IF CLOUDS SCOUR OUT (WHICH I THINK THEY
WILL). WILL PLAY IT CONSERVATIVE AND CARRY MINS IN THE UPPER SINGLE
NUMBERS TO LOWER TEENS.

MEDIUM RANGE MODELS (GFS/CANADIAN) HAVE TRENDED FASTER WITH THE
STORM SYSTEM FOR THURSDAY NIGHT-FRIDAY AS THE 500 MB LOW DOES NOT
DIG AS FAR SOUTH AS PREVIOUSLY INDICATED...WITH THE TROUGH AXIS
REMAINING NEUTRALLY TILTED AS IT SWING THROUGH US...WITH A
PROGRESSIVE COLD FRONT/OCCLUSION COMING THROUGH AROUND 12Z FRIDAY.
AS SUCH...HAVE INTRODUCED LOW CHANCE POPS FOR THURSDAY AFTERNOON
WITH THE WARM ADVECTION...AND BUMPED POPS TO 50 PERCENT FOR THURSDAY
NIGHT. ACCUMULATIONS LOOK TO BE LIGHT AT THIS POINT...BUT STILL ROOM
FOR THE MODELS TO BACKTRACK AND ALLOW FOR FASTER DEEPENING....AS THE
00Z EUROPEAN IS INDICATING A REAL CLOSE CALL.

&&

.MARINE...

A LOW PRESSURE SYSTEM WILL TRACK ACROSS THE NORTHERN GREAT LAKES/ONTARIO
TODAY...WITH STRONG WINDS (35 TO 40 KNOTS) DEVELOPING JUST AHEAD
OF AND BEHIND THE ASSOCIATED COLD FRONT THIS AFTERNOON INTO THIS
EVENING. GALE WARNINGS ARE NOW IN EFFECT FOR ALL MARINE AREAS.

THE DECREASE IN WINDS ON TUESDAY WILL BE SHORT LIVED...AS ANOTHER
RAPIDLY DEEPENING LOW PRESSURE SYSTEM IS EXPECTED TO TRACK THROUGH
THE SOUTHERN GREAT LAKES TUESDAY NIGHT...LIKELY RESULTING IN GALE
FORCE WINDS OVER SOUTHERN LAKE HURON BY WEDNESDAY MORNING...AS
ANOTHER STRONG SHOT OF COLD ADVECTION ARRIVES. WITH THE CURRENT
HEADLINES IN EFFECT...DECIDED TO HOLD OFF ON THE GALE WATCH FOR NOW.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.

LAKE HURON...
     GALE WARNING...LHZ361-LHZ362-LHZ363-LHZ421-LHZ441-LHZ442-LHZ443-
     LHZ462-LHZ463-LHZ464...FROM 1 PM MONDAY TO 5 AM TUESDAY.

     GALE WARNING...INNER SAGINAW BAY...FROM 4 PM MONDAY TO MIDNIGHT
     TUESDAY.

LAKE ST CLAIR...
     GALE WARNING...FROM 4 PM MONDAY TO MIDNIGHT TUESDAY.

MI WATERS OF LAKE ERIE...
     GALE WARNING...FROM 4 PM MONDAY TO MIDNIGHT TUESDAY.

&&

SHORT TERM...DRC
LONG TERM....SF
MARINE.......SF
AVIATION.....DRC

YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
354 AM EST MON DEC 29 2008

MIZ047-048-053-060-300930-
MIDLAND-BAY-SAGINAW-SHIAWASSEE-
354 AM EST MON DEC 29 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE TRI-CITIES REGION.

.DAY ONE...TODAY AND TONIGHT

A STRONG COLD FRONT WILL MOVE THROUGH SOUTHEAST MICHIGAN THIS
AFTERNOON...WITH WESTERLY POST FRONTAL GUSTS TO 40 MPH EXPECTED
LATE THIS AFTERNOON INTO EARLY THIS EVENING.

RIVER FLOOD WARNINGS REMAIN IN EFFECT FOR THE AREA.  PLEASE REFER
TO THE LATEST STATEMENT FOR DETAILS.../FLSDTX/.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

SNOW IS EXPECTED TO DEVELOP TUESDAY AFTERNOON...CONTINUING INTO
TUESDAY NIGHT...AS LOW PRESSURE TRACKS ALONG THE SOUTHERN MICHIGAN
BORDER. SNOWFALL ACCUMULATIONS OF 2 TO 4 INCHES APPEAR LIKELY.

SNOW ACCUMULATIONS ARE POSSIBLE AGAIN THURSDAY NIGHT INTO FRIDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT.

MIZ049-054-055-061>063-068>070-075-076-082-083-300930-
HURON-TUSCOLA-SANILAC-GENESEE-LAPEER-ST. CLAIR-LIVINGSTON-OAKLAND-
MACOMB-WASHTENAW-WAYNE-LENAWEE-MONROE-
354 AM EST MON DEC 29 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR MOST OF SOUTHEAST MICHIGAN.

.DAY ONE...TODAY AND TONIGHT

A STRONG COLD FRONT WILL MOVE THROUGH SOUTHEAST MICHIGAN THIS
AFTERNOON...WITH WESTERLY POST FRONTAL GUSTS TO 40 MPH EXPECTED
LATE THIS AFTERNOON INTO EARLY THIS EVENING.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

SNOW IS EXPECTED TO DEVELOP BY EARLY TUESDAY EVENING...CONTINUING
INTO TUESDAY NIGHT...AS LOW PRESSURE TRACKS ALONG THE SOUTHERN
MICHIGAN BORDER. SNOWFALL ACCUMULATIONS OF 2 TO 4 INCHES APPEAR
LIKELY...EXCEPT AN INCH OR LESS RIGHT NEAR THE OHIO BORDER.

SNOW ACCUMULATIONS ARE POSSIBLE AGAIN THURSDAY NIGHT INTO FRIDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT.

LCZ422-423-460-LEZ444-LHZ361>363-421-422-441>443-462>464-300930-
ST. CLAIR RIVER-DETROIT RIVER-LAKE ST. CLAIR-
MICHIGAN WATERS OF LAKE ERIE FROM DETROIT RIVER TO NORTH CAPE MI-
LAKE HURON FROM 5NM EAST OF MACKINAC BRIDGE TO PRESQUE ISLE LT
BEYOND 5 NM OFF SHORE-
LAKE HURON FROM PRESQUE ISLE LIGHT TO STURGEON POINT MI BEYOND 5NM
OFF SHORE-
LAKE HURON FROM STURGEON POINT TO ALABASTER MI BEYOND 5NM OFF SHORE-
OUTER SAGINAW BAY SW OF ALABASTER TO PORT AUSTIN MI TO INNER SAGINAW
BAY-INNER SAGINAW BAY SW OF POINT AU GRES TO BAY PORT MI-
PORT AUSTIN TO HARBOR BEACH MI-HARBOR BEACH TO PORT SANILAC MI-
PORT SANILAC TO PORT HURON MI-
LAKE HURON FROM PORT AUSTIN TO HARBOR BEACH BEYOND 5NM OFF SHORE-
LAKE HURON FROM HARBOR BEACH TO PORT SANILAC BEYOND 5NM OFF SHORE-
LAKE HURON FROM PORT SANILAC TO PORT HURON BEYOND 5NM OFF SHORE-
354 AM EST MON DEC 29 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF LAKE ERIE...LAKE
HURON AND LAKE ST CLAIR.

.DAY ONE...TODAY AND TONIGHT

GALE WARNINGS ARE IN EFFECT FOR ALL MARINE AREAS. REFER TO THE
LATEST MARINE FORECASTS FOR DETAILS.../GLFLH/.../GLFSC/...AND
/NSHDTX/.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

GALE FORCE WINDS APPEAR LIKELY ONCE AGAIN WEDNESDAY MORNING OVER
SOUTHERN LAKE HURON...WITH SMALL CRAFT/BRISK WIND ADVISORIES
LIKELY ELSEWHERE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT.

SF

YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).